Intraoperative and postoperative risk factors for respiratory failure after coronary bypass

Unlike preoperative events, the influence of intraoperative or postoperative events on respiratory failure after coronary artery bypass grafting (CABG) remains unclear. The purpose of this study was to identify intraoperative and postoperative risk factors that predispose respiratory impairment after CABG.

A single institutional database combined with a mandatory report submitted to the Cardiac Surgery Registry of the New York State Department of Health was used. A total of 8,802 consecutive patients who underwent primary CABG with or without a concomitant cardiac operation from January 1993 through December 2000 were included. Respiratory failure was defined as the need for postoperative mechanical ventilatory support longer than 72 hours. Univariate and multivariate logistic regression model was used in the analysis.

Of 8,802 consecutive patients (6,234 males and 2,568 females) who underwent CABG with or without a concomitant operation, 491 patients (5.6%) suffered from postoperative respiratory failure. Although univariate analysis identified 39 statistically significant preoperative risk factors for post-CABG respiratory failure, only six preoperative risk factors were statistically significant by multivariate analysis (p < 0.001). CPB time (in 30 minutes increments) was the only validated intraoperative variable that increased the risk of postrespiratory failure (odds ratio [OR], 1.2; p less than 0.0001). Postoperative events contributing significantly to an increased risk of post-CABG respiratory failure were (1) sepsis and endocarditis (OR, 90.4; p < 0.0001), (2) gastrointestinal bleeding with or without infarction and perforation (OR, 38.8; p < 0.0001), (3) renal failure (OR, 30.7; p < 0.0001), (4) deep sternal wound infection (OR, 11.3; p < 0.0001), (5) new stroke, intraoperative at 24 hours (OR, 9.3; p < 0.0001), and (6) bleeding that required reoperation (OR, 5.5; p < 0.0001). All perioperative variables together accounted for only 28.6% (R2) of the variation.

Respiratory function after CABG is readily influenced by postoperative occurrence of extracardiac organ or system complications.